Prince Andrew, whose close relationship with convicted sex offender Jeffrey Epstein has long been a source of controversy. Photograph: Dan Kitwood/Getty Images

A woman who claims that an American investment banker loaned her to rich and powerful friends as an underage “sex slave” has alleged in a US court document that she was repeatedly forced to have sexual relations with Prince Andrew.

The accusation against the Duke of York is contained in a motion filed in a Florida court this week in connection with a long-running lawsuit brought by women who say they were exploited by Jeffrey Epstein, a multi-millionaire convicted of soliciting sex with an underage girl after a plea deal.

The woman, who filed the motion anonymously, alleges that between 1999 and 2002 she was repeatedly sexually abused by Epstein who, she also alleges, loaned her out to rich and influential men around the world.

The document – a motion to expand an ongoing lawsuit relating to prosecutors’ handling of Epstein’s case with two new plaintiffs – alleges that the woman “was forced to have sexual relations with this prince when she was a minor” in London, New York and on a private Caribbean island owned by Epstein.

The prince is not a named party to the legal claim, which is directed against federal prosecutors. He has not had any opportunity to respond to the allegations in the legal claim.

The woman is said to have been 17 at the time, considered to be a minor in Florida.

In a 2011 Vanity Fair article, Prince Andrew denied any sexual contact with young women associated with Epstein.

Contacted on Thursday, Buckingham Palace declined to comment on the allegations contained in the court document. A palace spokesperson said the royal household would “never comment on an ongoing legal matter”.

However following publication of this article on theguardian.com, Buckingham Palace issued the following statement: “This relates to long-running and ongoing civil proceedings in the United States to which the Duke of York is not a party. As such we would not comment in detail. However, for the avoidance of doubt, any suggestion of impropriety with underage minors is categorically untrue.”

Another close associate of Epstein who is also accused in the lawsuit, Alan Dershowitz, told the Guardian that the woman’s accusations against himself were “totally false and made up”.

The Harvard law professor and esteemed criminal defence attorney who later advised Epstein on how to respond to the FBI’s investigation is accused in the court motion of having sexual relations with the woman when she was a minor and of witnessing the abuse of other minors.

On Thursday he told the Guardian: “There is no more strenuous denial than the one I am giving. I never met her. I don’t know her. I have never had sex with an underage person.”

He added: “This person has made this up out of cloth, maliciously and knowingly in order to extort money from Mr Epstein.”

Dershowitz, who has occasionally written op-ed articles for the Guardian, said he could not comment on the woman’s allegations against Prince Andrew or any other men, but he said her claims against him were demonstrably false and challenged her to file criminal charges against him.

“It is a totally fabricated charge in every possible way,” he said. “It just never happened.”

He said he was considering taking legal action to have Brad Edwards and Paul Cassell, the lawyers who filed the motion, disbarred for “knowingly filing … a false, malicious and defamatory statement in a lawsuit”.

Edwards said: “We have been informed of Mr Dershowitz’s threats of legal action and bar proceedings … we carefully investigate all of the allegations in our pleadings before presenting them.”

In a statement to the Guardian through her lawyers, the woman behind the allegations said she was being “unjustly victimised again”.

“These types of aggressive attacks on me are exactly the reason why sexual abuse victims typically remain silent and the reason why I did for a long time,” she said. “That trend should change. I’m not going to be bullied back into silence.”

The Guardian is aware of the identity of the plaintiff behind the allegations, but is respecting her wish to bring the case anonymously.

Andrew’s close relationship with Epstein – he visited him in New York two years after the American’s release from prison in 2009 – has long been a source of controversy. The Daily Mail reported in 2011 that the prince had broken off contact with the banker.

The duke had previously been accused of meeting Epstein’s young victims and possibly being aware of their sexual exploitation. However, this is the first time he has been named in a court document as a participant in any sexual activity with one of the young women allegedly trafficked by Epstein.

As the claim has only just been lodged, and as the duke is not a named party to it, he has not had the opportunity to formally file a defence or denial to the claims.

In 2006, the FBI opened an investigation into allegations that Epstein had been paying for sex with underage girls at his Palm Beach mansion for years. By the following year federal prosecutors said they had identified 40 young women who may have been illegally procured by Epstein.

In 2008, however, the federal inquiry was dropped after Epstein negotiated a deal with prosecutors in which he agreed to plead guilty to a relatively minor state charge relating to soliciting paid sex with a minor – a 14-year-old girl. He served 13 months of an 18-month sentence and is now a registered sex offender.

Many of his alleged victims have since reached out-of-court settlements with Epstein, who was once considered among the wealthiest investment bankers in the world.

However, two of Epstein’s alleged victims, referred to in court documents as Jane Doe 1 and Jane Doe 2, have brought a lawsuit arguing that federal prosecutors violated a victims’ rights statute by failing to consult them over Epstein’s secret deal.

The pair won a significant legal victory in July last year entitling them to see previously confidential documents from the plea bargain discussions between Epstein’s lawyers and federal prosecutors.

The court document filed this week containing allegations against Andrew is a motion to allow two more alleged Epstein victims, referred to as Jane Doe 3 and Jane Doe 4, to join the action.

Jane Doe 3 – the woman who made the accusations against Andrew – claims her contact with Epstein began when she was approached at the age of 15 by Ghislaine Maxwell, the daughter of the late media mogul Robert Maxwell and a close friend of Epstein.

The motion alleges that Maxwell “was one of the main women whom Epstein used to procure under-aged girls for sexual activities”. With Maxwell’s assistance, the document alleges, Epstein converted the girl into a “sex slave”, repeatedly abusing her in his private jet or his lavish residences in New York, New Mexico, Florida and the US Virgin Islands.

“Epstein also sexually trafficked the then-minor Jane Doe, making her available for sex to politically connected and financially powerful people,” the court document alleges. “Epstein’s purposes in ‘lending’ Jane Doe (along with other young girls) to such powerful people were to ingratiate himself with them for business, personal, political, and financial gain, as well as to obtain potential blackmail information.”

The motion alleges that Maxwell was “a primary co-conspirator in his sexual abuse and sex trafficking scheme” and that she also participated in the abuse.

The document goes on to allege: “Perhaps even more important to her role in Epstein’s sexual abuse ring, Maxwell had direct connections to other powerful individuals with whom she could connect Epstein. For instance, one such powerful individual Epstein forced Jane Doe #3 to have sexual relations with was a member of the British royal family, Prince Andrew (aka Duke of York).”

The document lists three locations where the woman alleges she was forced to have sexual relations with Andrew: Maxwell’s London apartment, Epstein’s private Caribbean island in what was allegedly “an orgy with numerous other under-aged girls”, and an undisclosed location in New York.

Requests made to representatives of Ghislaine Maxwell for comment had not been returned at the time of publication, but she has previously strenuously denied any involvement in procuring young girls for Epstein or any of his associates. In 2011 a spokesperson for Maxwell said she had never been contacted by any law enforcement agency in connection with the allegations.

However a statement issued on behalf of Maxwell after the Guardian published details of the lawsuit on Friday said the claims were “not new and have been fully responded to and shown to be untrue”. It added: “Ghislaine Maxwell’s original response to the lies and defamatory claims remains the same.”

The new motion alleges that Epstein instructed the girl “to give the prince whatever he demanded” and also instructed her to “report back on the details of the sexual abuse”.

The woman’s lawyers allege in their motion that, in addition to facilitating her alleged encounters with the prince and Dershowitz, Epstein trafficked her to “many other powerful men, including numerous prominent American politicians, powerful business executives, foreign presidents, a well-known prime minister, and other world leaders”.